19.Curling the stones lying in the house after all 16 have been played

20.Bowls the jack and the bowls that have been played considered together as a target area

21.against the headRugby from the opposing side's put-in to the scrum

Head

Edith. 1907--81, US dress designer: won many Oscars for her Hollywood film costume designs

head

The coma and nucleus of a comet when seen together. In this context ‘nucleus' means the diffuse starlike luminous condensation sometimes observed in the coma. The head generally contracts as perihelion is approached and expands again afterward. Remarkable changes in size, luminosity distribution, and the number of observed ‘nuclei’ can take place inside the head in a few hours.

Head

In general, the uppermost member of any structure. The upper horizontal cross-member between jambs, which forms the top of a door or window frame; may provide structural support for construction above.

Head

the anterior (or superior, in humans particularly) section of the body (separate from the trunk) of motile bilaterally symmetrical animals.

The upper division of the central nervous system, some sense organs, and the anterior sections of the digestive and respiratory systems are concentrated in the head. The anterior end of an animal, as yet undifferentiated but already structurally distinguishable from the rest of the body (for example, in the majority of worms) is called the cephalic end. The head, which is well-differentiated in some mollusks and especially in arthropods, became distinct from the cephalic end through the course of further evolution. Among the chor-dates, a differentiated head is present in the vertebrates (in connection with the progressive development of the central nervous system). Concentrated in the head of vertebrates are the brain, enclosed in the skull, the organs of smell, sight, and hearing; the organs of the oral and pharyngeal cavities, surrounded by the visceral arch; and, in lower vertebrates, the organs of the lateral line. In cyclostomes and the majority of fish the head is immovably attached to the spine. In terrestrial vertebrates the head is movable because of the separation of the cervical section of the body and the development of movable articulation of the skull with the spine. In amniotes (reptiles, birds, and mammals), with the formation of a clearly defined cervical section, the head is noticeably set apart from the torso (except in secondarily aquatic forms—that is, cetaceans and, among fossils, ichthyosaurs). In addition to mobility in the atlantooccipital joint, the head in amniotes may rotate together with the atlas around the dens axis, or epistropheus. The most mobile is the head of birds and the majority of mammals; this is associated with the progressive evolution of higher nervous activity and of the sense organs-olfactory, visual, and auditory.

Head development, which is of great importance in the evolution of vertebrates, is called cerebralization. In man, the head has anatomic features that are determined by the high level of brain development, the vertical position of the body, the transition to bipedalism, and the conversion of the hands to organs of work.

A. N. DRUZHININ

Head

(in hydraulics), a linear quantity expressing the specific energy (per unit weight) of a liquid stream at a particular point.

The total reserve of specific energy H of a stream (the total head) is defined by Bernoulli’s equation: H = z + (pv/γ) + (v2/2g), where z is the height of the point above the reference plane, pv, is the pressure of the liquid flowing with velocity v,γ is the density of the liquid, and g is the acceleration of gravity. The sum of the first two terms of the trinomial represents the sum of the specific potential energies of position (z) and pressure (pv/γ)—that is, the total content of specific potential energy, or the hydrostatic head. The third term represents the specific kinetic energy (the velocity head). The head decreases in the direction of flow. The difference between the heads in two cross sections of a real liquid H1 —H2 = hv is called the loss of head or lost head. For the motion of a viscous liquid in pipes the loss of head is determined by Darcy’s formula.

In the design of hydroengineering structures the head assumed in calculations is chosen in accordance with a given task. For example, for dams the head of the headrace is the depth of water in the headrace. In problems dealing with the flow of liquids or gases from orifices, the head is assumed to be the immersion depth of the “center of gravity” of the opening (for outflow of liquid) or the pressure differential (for outflow of gas). In hydroelectric power plants a distinction is made between the gross head (the difference between the elevations of the headrace and tailwater) and the net head (the gross head less the loss of head caused by hydraulic resistance).

The job will mean that someone gets a free delivery of our new menu for their family, and they will be asked to complete a feedback sheet which will go to head office and be used to continue our product development," he said.

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